Trailers commonly include a kingpin configured to attach to a fifth wheel assembly on a truck or tractor. The engagement between the fifth wheel assembly and the kingpin enables the truck or tractor to securely tow the trailer. Some conventional trailers include an adjustable kingpin assembly configured to pivot to adjust the ground clearance of the trailer. These adjustable kingpin assemblies may include a series of airbags or bladders configured to adjust the position of the kingpin assembly to achieve the desired ground clearance of the trailer. Accordingly, the adjustable kingpin assemblies enable the trailer to be positioned on the ground at a worksite, such as a hydraulic fracturing site, and then lifted off of the ground to facilitate transportation of the trailer to another location. The adjustable kingpin assemblies may also be configured to adjust the trailer between a relatively low ground clearance position and a relatively higher ground clearance position. For instance, it may be desirable to adjust the trailer into a relatively lower ground clearance position when the trailer is being transported on a highway, so that the trailer may safely pass under overpasses and through tunnels. In contrast, it may be desirable to adjust the trailer into a relatively higher ground clearance position when the trailer is being transported off-road or on other uneven terrain.
Conventional kingpin assemblies also include a ratchet mechanism configured to lock the adjustable kingpin assembly into the desired position based upon the desired ground clearance of the trailer. However, the ratchet mechanisms on conventional adjustable kingpin assemblies are prone to wear, which may cause the adjustable kingpin assembly to prematurely fail. Additionally, the engagement between the airbags and conventional adjustable kingpin assemblies is not completely maintained as the conventional kingpin assembly pivots into different opinions (i.e., conventional kingpin assemblies are not configured to compensate for the different angles between the kingpin assembly and the airbags due to the rotation of the kingpin assembly into different positions). Such angular misalignment between the airbags and the adjustable kingpin assembly may reduce the efficacy of the airbags or bladders in pivoting the kingpin assembly into different angular positions and may cause premature wear and failure of the airbags.